Biodegradability and Plastics : What you need to know

In this day and age, when environmental issues are trending all over the Media, this topic could not be more relevant. Media platforms have a huge ability to influence the public. The nature of the factual content they deliver can affect public behaviour and even influence legislation, especially on emotive topics like ‘plastic pollution’.

This is awesome, except when it’s not and incorrect information is shared instead. Perhaps by mistake or perhaps by a slip of the tongue, the wrong facts given out on a mass scale have the potential to undo years of research and hard work by scientists trying to influence positive change. And it could potentially be even more damaging to the environmental movements which they are trying to promote.

With the recent surge of pubic figures, media platforms and brands all eager to have a voice in the not-so-black-and-white topic of ‘plastic pollution’, I’ve written this blog in the hopes of clearing some confusion up.

What is plastic?

Plastic essentially derives from the greek word ‘Plastikos’, which means to mould. Plastic is a general term that can cover all sorts of materials, from polyvinyl to rubber. We’ve been using plastic to make useful items in society for thousands of years, the main forms have mostly been animal-based materials, such as ivory or turtle shell. Since the 1900’s (after a massive decline in elephant and turtle populations) we began altering the chemical formula of natural materials to make synthetic based alternatives.

Terms you really ought to know:

‘Biodegradability’ – this refers to a material’s ability to be eaten (decomposed) by bacteria or living organisms over a short period of time (e.g. 6months), to leave only carbon dioxide, water and biomass, which can all exist naturally in the environment.

‘Degradability’ – this just refers to a materials ability to break into smaller pieces.

‘Compostability’- this refers to a materials ability to biodegrade under natural conditions e.g. in a compost bin in a typical back garden.

To clarify, some types of plastic are only able to bio-degrade under specific industrial conditions (e.g. exposure to specific bacteria or heat). This means that biodegradable status alone, may not be sufficient to prevent environmental damage or hazards, should this type of plastic escape into the environment. Furthermore, plastics that are able to break down in a compost heap, may not break down in water and visa versa.

When is plastic actually bio-degradable?

The majority of plastic on the market originates from crude oil and is created by chemical processes known as ‘fractional distillation’ and ‘polymerisation’. These processes change the chemical formula of the material, making it incredibly difficult for any living organism to digest it. Instead, these fossil fuel derived plastics often just degrade under exposure to environmental conditions such as sunlight and waves. These small pieces are known as ‘microplastics’ and can lurk in the environment, to reek havoc for hundreds of years. For this reason, this type of plastic is not classed as biodegradable.

Are plant-based plastics biodegradable?

Plant-based plastics are a type of bio-plastic. Bioplastics can include plastics made from bacteria, sugar cane, vegetable products etc and are often referred to as greener alternatives as they are not derived from fossil fuels. However, the presumption that all bio-based plastics can biodegrade is also incorrect and can often cause more confusion.

The main thing to take into account here is the creation process. Though plant-based plastics are created using natural material, there are two types of end products:

Bio-based plastics and Synthetic bio-based plastics.

Bio-based – this simply refers to plastic that has been created from natural polymer chains including polysaccharides (e.g. starch / cellulose) without any further chemical processes. As it already occurs in nature, this particular type of plastic is usually biodegradable and compostable as a result. However, its short lifespan has limited applications in the commercial world.

Synthetic bio-based plastic– this type of plastic comes from naturally derived polymers too, it then undergoes further chemical reactions to make it stronger and more like it’s fossil-fuel derived counterparts in terms of physical properties. As a result, it is not biodegradable and usually needs to be collected, recycled and utilised in the same way as common plastic.

An example of this material would be Green- Polyethylene. This product is made from sugar cane, e.g. the sugar cane is used to produce ‘ethanol’ and then ‘ethylene’ and then ‘Polyethylene’, which has the same properties as it’s fossil fuel counterpart but creates 3 tonnes less CO2 in the creation process. This material will be implemented in Lego bricks later this year.

What are the pros and cons of bioplastics if they are not biodegradable?

The general selling point of bioplastic is the fact that it is not created from fossil fuels, a finite resource that can be incredibly detrimental to the environment. Creation through plant growth actually removes CO2 from the atmosphere and helps to reduce the impact of climate change.

The cons are dependant on each material and it’s important to know where it has been sourced from. Plant-based plastics often stem from monoculture growth, which can place a lot of pressure on an ecosystem in terms of habitat destruction, pesticides and water usage. It may also affect local communities, in terms of rising food costs, due to demand. However, this is not the case for all plant-based plastics.

With new technology and processes already under development, plastic creation is constantly developing. Useful bio-based plastics can now be created from food waste, organic gases and directly from bacteria, all of which eliminate the need for monoculture and can even potentially capture carbon emissions before they enter the atmosphere.

The only way to really promote sustainability is to keep educated and informed.

Sarah Roberts

Animal Behaviourist, specialised in Sharks, later became a Grizzly Bear guide. Now working across a number of platforms with different industries to connect as many people as possible with environmental issues.